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PubMed1992

Effects of a simulated microgravity model on cell structure and function in rat testis and epididymis.

A tail-suspension (TS) rat model used to simulate microgravity was tested for its effects on the anatomy, cell structure, and function of the testis and epididymis in sexually mature male rats. Rats suspended for 7 days without inguinal canal ligation exhibited a significant (P less than or equal to 0.05) reduction in testis weight compared with controls (1.55 +/- 0.04 to 1.1 +/- 0.02 g). Except for the liver, epididymis, and adrenals of TS rats and TS rats allowed to recover for 7 days, no significant (P less than or equal to 0.05) change was observed in the weight of other body and accessory sex organs. A histological examination of the testes and epididymides of model animals revealed disorganized seminiferous tubules and accumulation of large multinucleated cells and spermatids in the lumen of the epididymis. A significant (P less than or equal to 0.05) increase in serum luteinizing hormone (53.1 +/- 6.7 to 66.2 +/- 10.1 ng/ml) and follicle-stimulating hormone (257 +/- 25 to 305 +/- 38 ng/ml) was observed in TS nonligated rats, whereas serum prolactin and testosterone levels were observed to decline from 8.3 +/- 1.3 to 5.1 +/- 0.29 and 7.1 +/- 1.3 to 3.8 +/- 0.25 ng/ml, respectively. Decreases in testis protein content and testosterone levels of the testis, interstitial fluid, and epididymis were also observed in model animals. These data demonstrate that the suspension procedure used in the National Aeronautics and Space Administration TS model results in the testis and epididymis translocating into the abdominal cavity, causing cellular degeneration and organ dysfunction.

Animals↗
PubMed1999

Visualisation of biomedical datasets by use of growing cell structure networks: a novel diagnostic classification technique.

BACKGROUND: Medical research produces large multivariable datasets that are difficult to visualise and interpret intuitively. We describe a novel growing cell structure (GCS) technique that compresses multidimensional datasets into two dimensional maps with colour overlays that can be visually interpreted. METHODS: The two-dimensional map is self-discovered from the training set by distribution of cases to different nodes according to similarity between the cases at each node. Nodes are added to the map until there is no further significant reduction in error. The Parzen window method is used to estimate the probability distribution of the training cases, and this probability is converted to posterior class probabilities by use of Bayes' theorem. Classification performance can be assessed by means of receiver operating characteristic (ROC) curves. Colour maps of the values of each input variable at each node are constructed, which illustrate the relation between each input variable and the overall distribution of cases in the network map. FINDINGS: From a dataset of 11 input variables from 692 fine-needle aspirate samples from breast lesions, a 32-node network produced an area under the ROC curve of 0.96, which was not significantly different from that for logistic regression (0.98, z=1.09, p>0.05). Colour maps of the input variables showed that some variables had discrete distributions over exclusively benign or malignant areas of the network, and were thus discriminant, whereas others, such as foamy macrophages, covered both benign and malignant regions. INTERPRETATION: This technique produces dimensional compression that allows multidimensional data to be displayed as two-dimensional colour images. This envisioning of information allows the highly developed visuospatial abilities of human observers to perceive subtle inter-relations in the dataset.

Artificial Intelligence↗
PubMed1998

Flow cytometric assessment of cell structural and functional changes induced by acetic acid in the yeasts Zygosaccharomyces bailii and Saccharomyces cerevisiae.

Flow cytometry (FCM) was used with different viability dyes to assess changes in cell structure and function induced by acetic acid (AA) in populations of Zygosaccharomyces bailii (AA resistant) and Saccharomyces cerevisiae (AA sensitive). Kinetic changes in esterase activity, intracellular dye processing, and membrane integrity were monitored, and to detect those changes we used three assays involving fluorescein diacetate hydrolysis, FUN-1 processing, and propidium iodide exclusion, respectively. In S. cerevisiae, the decrease in the ability to process FUN-1 preceded the decrease in esterase activity, and there was loss of cell membrane integrity after incubation with AA. In Z. bailii, with higher AA concentrations, there was a similar decrease in the ability to process FUN-1, which also preceded the loss of cell membrane integrity. Changes in esterase activity in this yeast induced by AA treatment could not be monitored because the changes occurred independently of the presence of the acid. For control samples (untreated cells killed with 10% v/v of AA), the percentages of nonaltered cells as estimated by FCM and percentages of viable cells as estimated by colony forming unit (CFU) counts were identical. However, for cell samples treated for short periods with 3% (v/v) or less of AA, none of the dyes produced FCM results comparable to those produced by CFU counts.

Acetic Acid↗
PubMed1999

Probing plant cell structure and function with viral movement proteins.

Virus-encoded movement proteins are the principal strategy by which all plant viruses counter the primary physical defense of the plant to infection - the cell wall - to produce systemic infection and disease. Our understanding of how these proteins act at the molecular and cellular level has increased enormously in the past decade and ushered in an exciting new era of plant virology as an approach to investigating plant cell structure and function. The earliest studies focused on how movement proteins interacted with plasmodesmata, and were an important element in demonstrating the dynamic nature of these intercellular channels. Current efforts are focused on the role of movement proteins in coordinating the replication of viral genomes and the vectorial movement of the progeny genomes through the infected cell, as well as into adjacent cells. Movement proteins are thus providing unique approaches to unravel the fundamental mechanisms by which macromolecular transport is directed and integrated within and between plant cells.

Cell Wall↗
PubMed1996

Changes in parietal cell structure and function in HIV disease.

The mechanisms underlying acid secretory failure in patients with HIV disease are unknown. We evaluated, in a series of preliminary studies, changes associated with parietal cell structure and function in early and late HIV disease, in an attempt to elucidate possible underlying mechanisms. Gastric acid and intrinsic factor secretion, vitamin B12 absorption, and light and electron microscopic evaluation of gastric mucosa were evaluated in patients with early and late HIV infection (AIDS) and compared to non-HIV-infected controls. Immunolocalization of HIV-related antigens in gastric mucosa was also examined. Fasting gastric juice pH and intrinsic factor (IF) concentration in AIDS and HIV infected subjects were significantly different from controls (P = 0.012 and P = 0.025, respectively for pH, and 0.029 and 0.035 for IF; ANOVA LSD test). By contrast, maximal acid output (MAO) was significantly lower in AIDS, but not HIV-infected subjects (P = 0.043 and P = 0.322, respectively). Similarly, Schilling test phases 1 and 2 results were significantly lower in AIDS, but not HIV-infected subjects. Varying degrees of vacuolar degeneration of parietal cells were seen on light microscopy. On electron microscopy (EM), tubulovesicles were reduced and intracellular canaliculi dilated with striking loss of microvilli. Immunofluorescent staining with antibodies to gp120, gp41, p24, and p17 demonstrated positive punctate signals in the cytoplasm of gastric glands, which includes parietal cells. Immunogold EM with anti-gp120, localized predominantly to the microvilli of intracellular canaliculi in parietal cells. Abnormal secretory function of parietal cells occurs early in HIV disease, affects acid as well as intrinsic factor secretion, and is associated with morphological changes in the acid secretory apparatus.

Acquired Immunodeficiency Syndrome↗
PubMed1981

Changes in somatic cell structure during senescence of Volvox carteri.

Senescence of the terminally differentiated somatic cells of the green alga, Volvox carteri f. weismannia, was investigated by light, fluorescence, and electron microscopy. Viability of the somatic cell population, as determined by trypan blue or erythrosin B exclusion, showed a sharp reduction beginning 144 h after the somatic cells had lost the ability to divide. This increased mortality rate was correlated at the light microscopic level with a retraction of the somatic cell cytoplasm, a reduction in chloroplast autofluorescence (and total chlorophyll content), and a decline in the number of vacuoles which could be localized with 9-aminoacridine fluorescence microscopy. Nuclear fluorescence with acridine orange remained unaffected during this time. Lipid bodies increased in older cells, and total lipid analysis showed a sharp increase beginning 96 h after the somatic cells had stopped dividing. Electron microscopic comparison between young (48--72 h) and old (168 h) somatic cells showed a disorganization of chloroplast structure, a decline in the number of cytoplasmic ribosomes, and, substantiating the light microscopy, and accumulation of lipid bodies in the cytoplasm of the older cells. The results demonstrate progressive changes in somatic cell structure with age and are suggestive of cells under nutrient stress even though they are in nutrient medium. Therefore senescence and death of the V. carteri somatic cells may be caused, in part, by an inability to take up or utilize nutrients present in the culture medium.

Aging↗
PubMed2002

[The effect of image analyser noises in studies of cell structure].

Using image analysers, the influence of noises on the quality of images obtained from three types of digital CCD videocameras was studied. Algorithms for calculating the heterogeneity coefficient of cell structures have been proposed, which take into account the noises on the images. Application of procedures of image smoothing or averaging from a few shots, calculation of differences in heterogeneity coefficients of the object and a free field, and a combination of these methods have significantly reduced the influence of noises and increased the informativeness of texture features.

Algorithms↗
PubMed2005

Regional specialization in pyramidal cell structure in the limbic cortex of the vervet monkey (Cercopithecus pygerythrus): an intracellular injection study of the anterior and posterior cingulate gyrus.

The pyramidal cell phenotype varies quite dramatically in structure among different cortical areas in the primate brain. Comparative studies in visual cortex, in particular, but also in sensorimotor and prefrontal cortex, reveal systematic trends for pyramidal cell specialization in functionally related cortical areas. Moreover, there are systematic differences in the extent of these trends between different primate species. Recently we demonstrated differences in pyramidal cell structure in the cingulate cortex of the macaque monkey; however, in the absence of other comparative data it remains unknown as to whether the neuronal phenotype differs in cingulate cortex between species. Here we extend the basis for comparison by studying the structure of the basal dendritic trees of layer III pyramidal cells in the posterior and anterior cingulate gyrus of the vervet monkey (Brodmann's areas 23 and 24, respectively). Cells were injected with Lucifer Yellow in flat-mounted cortical slices, and processed for a light-stable DAB reaction product. Size, branching pattern, and spine density of basal dendritic arbors were determined, and somal areas measured. As in the macaque monkey, we found that pyramidal cells in anterior cingulate gyrus (area 24) were more branched and more spinous than those in posterior cingulate gyrus (area 23). In addition, the extent of the difference in pyramidal cell structure between these two cortical regions was less in the vervet monkey than in the macaque monkey.

Animals↗
PubMed1982

Cell dehydration during tissue freezing interpreted as Bradley isotherm desorption of structured cell water.

Tissue freezing without tissue death commonly shows ice formation in water outside but not inside of the cells. This observation conflicts with the expectation derived from the classical picture of the cell as a bag of liquid water with equal osmotic pressures and therefore equal depression of freezing points on both sides of the cell membrane. However, if intracellular water is structured in the form of multiple polarized layers adsorbed on cell proteins in accord with the Bradley isotherm, the prediction of theory is in harmony with experimental data.

Animals↗
PubMed2004

HPAF-II, a cell culture model to study pancreatic epithelial cell structure and function.

OBJECTIVES: Epithelial cells have distinct apical and basolateral plasma membrane domains separated by tight junctions. This phenotype is essential for the directional transport functions of epithelial cells. Here we characterized a well-differentiated pancreatic epithelial cell line to establish a useful model for understanding the mechanisms involved in the regulation of junctional complexes, polarity, and disease processes in the pancreas. METHODS: Immunofluorescence of cell junction marker proteins and electron microscopy were used to determine the presence of tight junctions, adherens junctions, and desmosomes. The functionality of tight junctions was tested by transepithelial resistance measurements and transepithelial permeability studies of nonionic molecules. Tight junction function in polarity was determined by laser scanning confocal microscopy. RESULTS: Immunofluorescence analysis in HPAF-II cells revealed tight junction localization of ZO-1, occludin, and claudin-4; adherens junction localization of E-cadherin and beta-catenin; and desmosomal localization of desmocollin. Transmission electron microscopy showed the presence of tight junctions, adherens junctions, and des-mosomes, and freeze-fracture electron microscopy revealed the presence of distinct anastomosing tight junction strands. Transepithelial electrical resistance and permeability measurements revealed functional tight junctions. In addition, 3-dimensional images of the monolayer generated by laser scanning confocal microscopy revealed that HPAF-II cells show polarity. Immunoblotting and RT-PCR analyses revealed high expression levels of E-cadherin and Na,K-ATPase beta-subunit but low levels of the transcription factor Snail in HPAF-II cells compared with MiaPaCa-2 cells. CONCLUSION: The HPAF-II cell line is a well-differentiated human pancreatic carcinoma cell line that should be useful as a model for studies aimed at understanding epithelial polarity, regulation of junctional complexes, and disease processes in pancreas.

Adherens Junctions↗
PubMed2004

Cardiac physiology at the cellular level: use of cultured HL-1 cardiomyocytes for studies of cardiac muscle cell structure and function.

HL-1 cells are currently the only cardiomyocyte cell line available that continuously divides and spontaneously contracts while maintaining a differentiated cardiac phenotype. Extensive characterization using microscopic, genetic, immunohistochemical, electrophysiological, and pharmacological techniques has demonstrated how similar HL-1 cells are to primary cardiomyocytes. In the few years that HL-1 cells have been available, they have been used in a variety of model systems designed to answer important questions regarding cardiac biology at the cellular and molecular levels. Whereas HL-1 cells have been used to study normal cardiomyocyte function with regard to signaling, electrical, metabolic, and transcriptional regulation, they have also been used to address pathological conditions such as hypoxia, hyperglycemia-hyperinsulinemia, apoptosis, and ischemia-reperfusion. The availability of an immortalized, contractile cardiac cell line has provided investigators with a tool for probing the intricacies of cardiomyocyte function. In this review, we describe the culture and characterization of HL-1 cardiomyocytes as well as various model systems that have been developed using these cells to gain a better understanding of cardiac biology at the cellular and molecular levels.

Animals↗
PubMed1989

Bone lining cells: structure and function.

Bone lining cells (BLC's) cover inactive (nonremodeling) bone surfaces, particularly evident in the adult skeleton. BLC's are thinly extended over bone surfaces, have flat or slightly ovoid nuclei, connect to other BLC's via gap junctions, and send cell processes into surface canaliculi. BLC's can be induced to proliferate and differentiate into osteogenic cells and may represent a source of "determined" osteogenic precursors. BLC's and other cells of the endosteal tissues may be an integral part of the marrow stromal system and have important functions in hematopoiesis, perhaps by controlling the inductive microenvironment. Because activation of bone remodeling occurs on inactive bone surfaces, BLC's may be involved in the propagation of the activation signal that initiates bone resorption and bone remodeling. Evidence also suggests that BLC's are important in the maintenance of the bone fluids and the fluxes of ions between the bone fluid and interstitial fluid compartments for mineral homeostasis.

Animals↗
PubMed1976

Unusual cell structures in tumor-like formations of Gracilaria (Rhodophyta).

This paper deals with electron microscopic observations on cultivated plants of the marine red alga Gracilaria verrucosa which developed simple galla; also sea collected material, without galls, had been studied. The galls showed unusual but characteristic cell structured, caterpillar-like bodies, containing rows of fusiform bodies. These were found mostly in the cytoplasm near the plastids, in one case connected with the endoplasmic reticulum, occasionally even inside the nucleus, and are described here, as far as we know, for the first time. It does not seem probably that the caterpillar-like bodies represent mitochondria or bacteria, but the hypothesis that fusiform bodies are related to virus-like structures is discussed. The normal tissues as well as the gall tissue of the laboratory plants contained, besides plastids typical for the red algae, another type of plastids characterized by tubular thylakoids.

Cytoplasmic Granules↗
PubMed2005

Deterministic projection by growing cell structure networks for visualization of high-dimensionality datasets.

Recent advances in clinical proteomics data acquisition have led to the generation of datasets of high complexity and dimensionality. We present here a visualization method for high-dimensionality datasets that makes use of neuronal vectors of a trained growing cell structure (GCS) network for the projection of data points onto two dimensions. The use of a GCS network enables the generation of the projection matrix deterministically rather than randomly as in random projection. Three datasets were used to benchmark the performance and to demonstrate the use of this deterministic projection approach in real-life scientific applications. Comparisons are made to an existing self-organizing map projection method and random projection. The results suggest that deterministic projection outperforms existing methods and is suitable for the visualization of datasets of very high dimensionality.

Algorithms↗
PubMed1982

Human cytotoxic T cell structures associated with expression of cytolysis. I. Analysis at the clonal cell level of the cytolysis-inhibiting effect of 7 monoclonal antibodies.

Monoclonal antibodies (mAb) derived from BALB/c mice immunized with human anti-HLA-A2 cloned cytotoxic T lymphocytes (CTL) were screened for their ability to block, in the absence of complement, the cytolytic activity of the immunizing CTL clone. Eight cytolysis-inhibiting mAb have been derived. One of these was directed against a monomorphic determinant expressed on HLA-class I molecules and thus probably inhibited cytolysis via a target cell antigen-masking effect. The 7 other mAb recognized "CTL function-associated structures" and did not have to interfere with target cell antigens in order to inhibit cytolysis. F(ab')2 and Fab fragments of these 7 mAb were also inhibitory. Competitive inhibition of binding and preliminary biochemical analysis suggested that these 7 mAb defined on cloned CTL various epitopes of a structure of 30 kDa disulfide-bonded into several multimeric forms when analyzed without reduction. The inhibitory effect of these 7 mAb has been investigated on a series of short-term (1 month) and long-term (greater than 10 months) expanded cloned CTL lines derived in vitro from an in vivo allosensitized individual exhibiting various specificities. Unexpectedly, only 10% of these CTL clones were inhibited. Flow cytofluorimetric analysis further revealed that noninhibited and inhibited CTL clones expressed similar amounts of the 30-kDa structure. Consequently, the inhibition of CTL was heterogeneous when analyzed at the clonal level and not simply related to the presence or absence of this structure. Furthermore, the ability of CTL clones to be inhibited appeared to be unrelated to their HLA-A, B or C specificity or to their lytic activity. The connections between this mAb-defined structure and CTL function are discussed.

Animals↗
PubMed1983

Glycoprotein-bound large carbohydrates of early embryonic cells: structural characteristic of the glycan isolated from F9 embryonal carcinoma cells.

The high-molecular-weight glycopeptides characteristic of early embryonic cells were isolated from F9 embryonal carcinoma cells grown in vitro and also from the cells grown in vivo as subcutaneous tumors. The two preparations had similar carbohydrate compositions. The major components were galactose and N-acetylglucosamine (molar ratio 1:0.86) in the glycan isolated from the cultured cells. In addition, small amounts of fucose, N-acetylgalactosamine and mannose were present. The glycan from the in vitro grown cells was found to have a molecular weight of more than 10,000 by gel filtration after mild alkaline treatment or hydrazinolysis. The structural characteristics of the core portion of the glycan were studied by using the radioactively labeled glycopeptide from the in vitro grown cells. Methylation analysis provided the following informations. 1) The glycan was highly branched at galactosyl residues. 2) Large numbers of galactosyl residues were also present at non-reducing termini. 3) Monosubstitution of galactose occurred at C-3. 4) Glucosamine residues were mainly monosubstituted. That the disaccharide GlcNAc-Gal was the major structural unit of the glycan was suggested by the isolation of the deacetylated disaccharide after alkaline thiophenol cleavage followed by acid hydrolysis. Furthermore, methylation analysis of the glycan from the in vivo grown tumors indicated that monosubstitution of glucosamine occurred at C-4 and that disubstitution of galactose occurred at least mainly at C-3 and C-6. We propose that the basic structural unit of the core portion is 4GlcNAc 1 leads to 3Gal, and that the galactosyl residue serves as a branching point at C-6. Thus, the structural unit of the core portion of the large glycan appears to be the same as that of lactosaminoglycans found in adult cells.

Amino Acids↗